The objective of this proposed project is to develop recombinant antibodies against 75 cancer-related proteins. In the Phase I study, we have demonstrated that multiple antibody clones could be isolated from a large yeast displayed human antibody library. The isolated antibodies exhibit high affinity (lOW nM to sub-nM) and high specificity compariable to monoclonal antibodies derived from hybridoma technology. In parallel, the technology platform was optimzed to support more robust full length IgG display and consistent antibody expression in yeast cells. In this proposed Phase II project, we propose to isolate antibodies against 75 cancer related antigens developed by NCI's Clinical Proteomic Technologies Initiative using AvantGn's proprietary yeast display antibody library. The isolated antibodies will be characterized in terms of affinity (on and off binding constants) and specificity, and for performance in commonly used assays such as immunoprecipitation, and/or Western blot, with the goal of identifying 2 distinct antibody clones per antigen suitable for developing ELiSAs. These antibodies will be further intergrated into proteomic research platforms in collabration with NCI's Clinical Proteomic Technologies Initiative.